thoma



Jan. 17, 1928. 1,656,544

H. THOMA ROTARY PUMP AND MOTOR Filed March 26, 1924 3 Sheets-Sheet 1 Hans T O E) HIS ATTOR/VEY.

Jan. 17, 1928. 1,656,544

. H. THOMA ROTARY PUMP AND MOTOR Filed March 26, 1924 3 Sheets-Sheet 2 HI THOMA ROTARY PUMP AND MOTOR Filed March 26, 1924 3 Sheets-Sheet 3 any //Vl/E/VTOR.'

' Hans Thoma. BYH/S ATTORNEY. 671

Patented Jan. 17, 1928.

} N STATES Pars HANS THOMA, F IJIUNICH, GERMANY.

no'renv PUMP AND MOTOR.

Application filed Marcn ZG,1924, SerialNo. 702,103, and in Germany November 25, 1922.

This invention relates to rotary motors and pumps of the kind in which a rotor have ing radial cylinders therein, with pistons in the cylinders, rotates in adrum which is eccentric inrelation thereto, the pistons bearing against the inner surface ofthe drum, and liquid being supplied to, and discharged l'rom, the said cylinders by means of ducts and portsin a nonrotating trunnion upon which the rotorrotatcs.

One object of my invention is to reduce the lateral thrust on the trunnion, due to the pressure of the liquid, generally oil,and another object is to provide improved means for regulating the speed of the motor in apparatus wherein a pump and a motor, both of the kind referred to, are so combined that liquid propelled by the pump is used.

for driving the motor.

The invention is illustrated in the accompanying drawing in which,

Fig. 1 is a horizontal section of a pump or motor, and

Fig. 2 a 'verti different planes.

Fig. 3 is a cross section of the rotor trunmen, to a larger scale, and

Figs. 4 and 5 are a side view and a plan cal section thereof in two viewof the said trunnion respectively.

Fig. 6 shows diagrammatically the 00111 bination of a'pump and motor as hereinbefore referred to, and

Fig? is a horizontal section of part of this apparatus.

Fig. 8 is a development of the surface of a cam forming part of the mechanism shown in Fig. 7.

Referring 1 has fixed therein a trunnion 2, round which rotates the rotor 23, one wall of the casing having a bearing for one end of the trunnion, the other end of which is unsupported. In the rotor 3 are the radial cylinders 4, with pistons 5 therein. The outer end of each piston has a cross-head 6. whose diameter exceeds the diameter of the piston, This crosshead is traversed by a pin 7 having at its projecting ends gudgeons for rollers 8, which run on the inner circumferential surface of a drum 9. The latter is rotatable on ball bearings 12 mounted on a holder 10, which is adjustable, dian'ietrally of the casing 1, between guides 10, the adjustment being effected by means of a screw spindle 10. This adjustment enables the eccentricity oi? the drum 9, and consequently the stroke of first to Figs. 1 and 2, the casing the pistons 5, to be regulated; it also enables the direction of discharge of the pump or of rotation of the motor to be reversed. i

The supply and discharge of the driving or driven fluid, generally oil, takes place throizgh conduits 13 and 14- in the, trunnion 2 and radial ports 15 and 16 in the rotor, opening into the cylinders. in order to pro.- vide for lubrication oi": the rollers 8 there are ducts l7 and .18 in the pistons and cross heads. In order to relieve the central pivot or trunnion 2 to some extent of lateral thrust, there are two annular grooves 19 in the said trunnion near the ports 15 and 16. These grooves limit, to a defined length of the trunnion, the spreading of oil along the surface oi the trunnion, and become filled with oil which has been forced alongthe surface or the trunnion from one or other oi the ports, and the grooves thus constitute circular channelsfilled with oil, whichtransmil; fluid pressure from one side of the trunnion to the other and to some extent balance the thrust. Additional reliefis'a'f-- torde'd by branch channels 20, forming loops of the channels 19 and bounding'rectangular surfaceportions 21 of the trunnion on the suction side.

The rotor is connected with the driving or driven shalt 22 by means of a coupling plate 28 having dogs 23 which engage recesses in the rotor, and having also a dog 25' which engagesa slot in the endof the shaft. The dogs 23 do not entirely fill the recesses wherein they lie, and the plate .does

not entirely fill the space between the rotor and the shaft, so that a slight amount of axial and rotational play is allowed.

Figs. 6 and 7 show an example of apparatus in which a rotary motor and a rotary pump, both constructed in accordance with my invention, are combined, 34 being the pump, which has a driving pulley 35, and 36 being the motor, which may be used, for example, for driving a machine tool or lathe. An oil container 87 is connected to thepump and the motor. The pump 34: sucks oil from said oil-container, whilst the motor 36' delivers the spent oil to the container. i

' In order to prevent overheating of the oil the oil container is of substantial size in relation to the capacity of the pump and motor,

and it is placed below the motor and pump in the foot of the machine frame, where massive metal parts are available for conducting heat.

In the case of a lathe, it is important to be able to obtain definite speeds of the driven shaft by adjusting the gear. lVith the apparatus shown in Figs. 6 and 7 regulation can be effected, up to the point at which the pump attains its maximum output, by regulating the eccentricity of the drum in the pump, as described with reference to Figs. 1 and'2. The additional regulation, for obtaining further increase of speed, can. be effected by decreasing the eccentricity of the drum in the motor, this being done without altering the maximum eccentricity given to the pump drum. To this end there is mounted on an axle at one side of the pump and motor, a cam cylinder 86 (Fig. 7 or 8) having at its circumference a channel 87. This channel is not continuous, and consists of a straight portion with curved portion at each end Within this channel run two rollers 88, 89, mounted at the ends of arms 90 connected respectively to the adjustable holders of the drums in the pump and motor. The cam cylinder can be rotated by means of a hand wheel 98 and suitable gearing. By rotation of the cam while the roller 88 is in one of the curved portions of the channel 87 the drum in the pump is moved, and while this movement is taking place the roller 89 is in the straight part of the channel, so that the drum in the motor is not moved.

- When the pump drum has been moved to its position of maximum eccentricity, continued rotation of the cam results in the roller 89 engaging the other curved portion of the channel 87, whereas the roller 88 engages the straight part of the channel. Consequently the motor drum is moved transversely of the motor axis, whereas the pump drum remains stationary. Fixed to the cam axle is a pointer 91, which works on a dial having a scale marked thereon, the scale indicating the rates of revolution of the motor obtainable by setting the cam in the positions indicated by the pointer.

Claims:

1. A. hydraulic variable speed gear consisting of a pump and a motor driven by the movable to. different positions of eccentricity with relation to said rotor, pistons in said.

cylinders, crossheads fixed to said pistons,

rollers mounted on said crossheads in contact with the inner circumference of the drum, a bearing, and a trunnion upon which said rotor is rotatable, said trunnion having one of its ends fixed within said bearing, the other end being unsupported, and said trunnion having at opposite sides thereof ports for the fiow of liquid to and from said cylinders, and having also on each side of said ports an annular groove for limiting the spreading of liquid from theports to a. defined length of the trunnion, and regulating mechanism whose actuation in one direction first causes movement of the pump drum to a position of maximum eccentricity in relation to the pump rotor, the motor having its maximum capacity during that movement, and then causes movement of the motor drum reducing its eccentricity, Without moving the pump drum.

2. A hydraulic variable speed gear, according to claim l, in which the regulating mechanism comprises adjustable holders for the pump drum and the motor drum respectively, movable for varying the eccentricity ofsaid drums, a cam having a groove which has a straight portion and curved portions in continuation ofsaid straight portion, and two rollers engaged with said groove, mounted on said adjustable holders respectively, whereby rotation of said cam'imparts movement to said holders when the respective rollers are in the curved portions of said groove, said rollers and said cam being so positioned that when m the course of rotation of said cam either of, the rollersis in the straight portion of said groove the other roller is in one of the curved portions of said groove.

HANS THOMA. 

